Diastereomeric 7-ureidoacetyl cephalosporins. I. Superiority of 7.ALPHA.-H-L-isomers over D-isomers.

Abstract
The synthesis and in vitro structure-activity relationship of 7-ureidoacetyl cephalosporins carrying various substituents in the 3-position, compounds that showed an enhanced broad spectrum of antibacterial activity, was outlined. Contrary to most of the previous observations with diastereomeric isomers of cephalosporins, the L-side chain isomers also are very potent antibiotics and are even more active inhibitors of certain .beta.-lactamase-producing gram-negative bacteria than the corresponding D-side chain isomers. SQ 69,613, 7.beta.-[[L-[(aminocarbonyl)amino]-2-furanylacetyl]amino]-3-[[(1-methyl-1H-tetrazol-5-yl)thio]methyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, Na salt, the most active compound tested, except for activity against staphylococci, was as active in vitro as cefamandole.